It's quite difficult to predict that whether you will get  seat or not as  cut off marks for medical colleges keeps changing every year  depending upon various factors like  number of students that appeared in the exam, kind of marks obtained by them , toughness level of the examination etc.

But when we go through previous data then it suggests that with 421 marks   you hold a low chance to get a seat in a Government Medical College

For example,
In Neet 2019, the lowest marks that got a seat in Government Medical College for sc category under Bihar state quota was 449 marks and it was for Government Medical College, Bettiah

With your marks you have chances for govt quota seats   in private medical college and deemed universities

To get the list of colleges in which you have chances, you can go through our college predictor at

https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer

It gives you a personalized report with top college in which you have chances for admission , with the help of predicted colleges you can make better choice while filling your choices of colleges during your counselling

Thankyou